An advisory panel to the Food and Drug Administration recommended the agency approve what could become the first prescription drug in the U.S. derived from the marijuana plant, as a treatment for people with rare forms of epilepsy.

A committee on Thursday voted 13-0 that the risk-benefit profile was favorable for
GW Pharmaceuticals
GWPH -5.32%
PLC’s drug, cannabidiol, to treat seizures associated with Lennox-Gastaut syndrome or Dravet syndrome in patients 2 years of age and older. The rare disorders involve frequent or difficult-to-treat seizures, often afflicting children.

The FDA is expected to decide by the end of June whether to approve the drug for sale. The agency isn’t required to follow the advice of its advisory committees but usually does. GW Pharmaceuticals proposes to call the drug by the brand name Epidiolex.

Cannabidiol is derived from the cannabis plant, also known as marijuana. U.K.-based GW Pharmaceuticals says the solution, taken by mouth, is made from a proprietary strain of cannabis designed to maximize a therapeutic component while minimizing components that produce euphoria. GW Pharmaceuticals grows the plants in the U.K.

In company-sponsored clinical studies, cannabidiol reduced the frequency of patients’ seizures. In one study of 120 children and young adults with Dravet syndrome, cannabidiol reduced the median frequency of convulsive seizures to 5.9 a month from 12.4 before treatment, while patients getting a placebo saw minimal reductions, according to results published last year in the New England Journal of Medicine.

The drug is associated with some adverse events, including gastrointestinal problems and abnormal liver-function test results. But FDA officials on Thursday said they believed the risks were manageable if cautionary language is placed in the drug’s prescribing label, and if the agency monitors liver risk after the drug is on the market.

FDA officials also said the drug doesn’t appear to have abuse potential, citing minimal reports of euphoria in patients who took the drug in clinical studies.

Several parents of children with epilepsy testified before the panel, saying cannabidiol helped reduce seizures and improve quality of life.

“I think the case has been made, and there’s obviously a real need and safety concerns are negligible,” said FDA committee member Harriet de Wit, a professor in the department of psychiatry and behavioral neuroscience at the University of Chicago.